Cylindrical domestic refrigerator



Dec. 7, 1948.

' Filed May 26. 1945 W. L. MORRISON CYLINDRICAL DOMESTIC REFRIGERATOR Sheets-Sheet 1 Dec. 7, 1948.

W. L. MORRISON CYLINDRIQAL DOMESTIC REFRIGERATOR Filed May 26, 1945 3 Sheets-Sheet 3 I %y M ratus and has for one purpose matica Patented Dec. 7, 1948 -UNITED STATES! PATENT OFFlCE oYLINpRIoAL DOMESTIC REFRIGERATOR wiuaran Morrison, Lake F rest, n1. 7 Application May 26, 1945, Serial-No. 596,048

r 16 Claims. (01. rig-+116),

This invention relates to refrigerating appato provide an improved evaporator.

Another purposeis to provide an evaporator which circumferentially defines and surrounds =1 an open topped storage area;

Another purpose is to provide an evaporator which shall beeconomical and simple to manufacture. 1

Another purpose is to provide an evaporator unit which permits the employment of a minimum volume of a volatile refrigerant. x a I Another purpose is to provide an evaporator surrounding a storage space, which evaporator distributes the =volatile evaporant substantially uniformly throughout the area of the evaporator which surrounds thestorage space.

Another purpose is to provide improved means for maintaining a high" temperature about the top of the unit, above the ,.e vaporator where it is contacted by warm outside air, at a line of demarcation between chilled and; not chilled areas. .Another purpose isy-to'provide an evaporator structure which includes a receiver.

Another purpose is to provide an evaporator container, which may be made of two generally cylindrical members, which, together, define both an evaporator and a receiver, the inner of the two; members forming the storage space eof the refrigerator.- q

Other purposeswill appear from time to time .in the course of the spec ification and claims.

skids 4; The evaporator is illustrated as having anouter cylinder 5 and an inner cylinder 6. The inner and outer cylinders may be welded or otherwise secured toeaich other at their upper and lower edges asv shown in Figures 3, 5 and fijat "I and 8. I may ior'example employ seam weld.- ing. The cylinders in the completed container or evaporator, are spaced sufiiciently apartto define arefrigerant receiving space which extends entirely about theevaporator and substantially from top to bottom of the evaporator; This may be a space of .very low clearance. It mayior example approximate .026" to .028, this; being given as an example rather than as a rigid restriction to any particular space range. The point is thatit is practical, in the present'structure, to employ a close clearance between the two cylinders. s v I In the form of the device herein shown, the inner cylinder 6 is shown as substantially atrue cylinder although it might be slightly tapered and has a smooth, preferably unbroken cylindrical, face which circumfererrtially surrounds I illustrate the invention moreor'less diagrainlly in the accompanying drawings, where- I ,Figure 11s a side elevation;

Figure 2 is a'section, on ,an enlarged scale, on the line 22 of Figure 1;

F gure 3 is asection on the'line' 3 3 ofFigure 2; l l a w Figure 4 is a section on the "line 4-4 of. Fig- -,ure3;,

Figure 5 is a section on the line' 5-5 of-F'igure 2;

Figure 6 is a section on the line6--.B of Figure 2; and

Figure 7 is a vertical axial section, on an enlarged scale, illustrating a variant form'of evap- .orator and receiverfstructure. 1 Like parts are indicated by likecharacters L throughout the specification and drawings.

In the invention herein illustrated, lsemploy a base I which maybe generally flat and shown as having a generally, plane top surface land a generally fplane bottom surface mounted on and defines the storage space of the refrigerator unit. .The outer cylinder is provided with two outer beads or concave-convex projections 51,-. Ill. These serve as distributors for the refrigerant which is shown as entering the bottom inlet, p assage H and escaping through the topoutlet passage l2. s g r s I illustrate the upper distributor 9 as substantially larger than the lower distributor l0 because it receivesgas whereas the bottom distributor receives. the refrigerant. as I an unexpanded liquid. The two cylinders may be spaced L apart by the indented projections I3. on the outer cylinder, of which any suitable number may be employed for providing a uniform effective spacing between the two cylinders and may also employ intermediate smaller distributor beads as shown-at 14 which are shown as extending entirely aboutthe' outer cylinder. One or ino're may be employed, depending-lupon the heightof a the evaporator.

After the two-cylinders have been formedand joined, I'may'apply any suitablebottom rnember 15 with its centering projection i511, whichmay be welded to the cylinders as at l6.

I may find it advantageous to roll both the inner and'the outer cylinder from) sheet stock. "They may be rolled into substantiallycorrectforrniand dimensions and may then be seam welded or otherwise secured at their abutting edges. In forming the outercylinder 5, I find it advantageous to pass the sheet stock through formingrolls 3 which roll out the manifolds or distributors 9, Ill and M, and which also form the dimples or spac-- ing indentations R3, at the same time the integral heat interchanger 5a is formed at the top of the outer cylinder. Since the forming tools do not of themselves form part of the present invention, I do not illustrate them. It will be understood, however, that I may employ any suitable forming rolls or forming tools for producing requisite shape or form of the two cylinders. After the two cylinders have been initially formed, the inner cylinder and the outer cylinder are interfitted. For ease of interfitting and for accuracy of manufacture, I find it desirable initially to form the cylinders with a somewhat larger clearance than their final clearance. Thereafter and preferably before they are permanently secured together, I

may employ any suitable internal expander for directing a substantially uniform outward thrust throughout the areaof the inner face of the inner cylinder 6. The thrust is continued until the inner cylinder engages the dimples l3 which provide means for uniformly spacing the two cylinders apart. Whereas I have illustrated and described the use of spacing dimples integral with the outer cylinder 5, it will be understood that any other suitable spacing means may be employed. Or under some circumstances, the spacing means may be dispensed with' although they constitute an efficient mode of obtaining a uniform clearance between the inner face of the outer cylinder 5 and the outer face of the inner cylinder 6. Thus when the expanding tool causes the inner cylinder 6 to engage the points of the dimples l3, then the two cylinders are properly spaced. The forming tool forms'the parts to a true cylinder.

It will be noted that the distributors 8 and Hi are spaced somewhat inwardly of the edges of the cylinders. Also the integral interchanger 5a, which is shown as above the top distributor 9, is spaced somewhat downwardly from the upper edge of the final cylindrical structure, This is advantageous as giving adequate'space for seam welding at the points I and 8. The distributors or manifolds so placed do not interfere with the use of a wheel type seam welder. The two cylinders are also seam welded at la between the heat interchanger 5a and distributor 9.. Either during the last welding operation or directly afterwards, I may add the bottom element i5. Any

suitable form of bottom may be employed. I may for example employ a drawn cup bottom. However, the bottom may be added either before or after or at the time of welding the two cylinders 5 and 6.

It will be understood that whereasI find it convenient and economical to form the outer and 'inner cylinders 5 and 6 of sheet stock, welded along a longitudinal seam. I may also employ drawn cylinders. For e'xampleQit isunder some circumstances advantageous to draw the inner cylinder in order to have it seamless: In that event thebottom may be integral with the inner erating apparatus comprising a motor 22 and a compressor 23, driven from the motor by a belt 2 3. The gas, when compressedby the compressor, passes out through the pipe 38 and is then deliver-ed to the top of the condenser 39. The liquid then passes from the condenser through the pipe so into the receiver 4|. The refrigerant then passes from the receiver M by the duct 42 to the integral heat. exchanger 5a. which is formed between the innerand outer cylinders 5. and 5, The refrigerant passes around this heat interchanger and after having passed about almost 360 degrees, it flows along the passage 19c to any suitable expansion valve 52 with any suitable thermostatic. control 54. The refrigerant, now at low pressure, passes along the duct II to the lower distributor or manifold ll) of the outer cylinder 5. The discharge passage I2 returns the gas from the upper enlargement or distrbutor 9 to the compressor.

The compressorcondenser unit may be mounted upon a lateral extension ia of the base i and may be surrounded by any suitable housing s0. The evaporator is shown as positioned and supported on a block or disc SI" of insulating material, which is initially held against lateral movement on the base i by the dowel 62.. The member 6 lis recessed to receive the centering projection [5a. 63 is any suitable concentric surrounding housingwhich constitutes the exterior wall of the refrigerator cabinet. It may be of relatively thin relatively flexible material, such as sheet metal. When the insulation 64 is crowded down into the space between the evaporator and the outer wall 63, a firm structure isprovided' which surrounds and is reinforced by the evaporator. Any suitable top cover 65 may beemployed for the insulation and a removable top closure 66 is used to protect the storage area from above. Any suitable insulation 6'! may surround the upper portion of the evaporator care being taken to avoid the use of any heattransmitting material. The cover 66 is cylinder and the inner cylinder will be outwardly expanded against the outercylinder, thewelding following the final expansion.

It will be understood that under some circumstances it may be advantageous to weld the cylinders together at top and bottom before the final expansion of the inner cylinder in relation to the Y outer, takes place. I

The refrigerating cycle and structure do not of themselves form a part of the present invention. .Any suitable refrigerating apparatus maybe used. In the drawings 1 have illustrated a refr g at all points located above the space surrounded by the evaporator and does not extend down into the pool of cold air which is maintained in the space surrounded by the evaporator.

Referring to Fig. 7,1 illustrate a variant form of evaporator in which the receiver'is formed as part of the evaporator structure. Thus I' illustrate an inside cylinder 6a and an outside cylinder 5ll.- In the outside cylinder I form the upper distributor 9a and the lower distributor Illa. Any suitable spacing means 'l3amay be employed to separate the two cylinders toform the evaporator space. I may also employ intermediate distributors Ma, whichmay also be formed in the outercylinder." Above the upper distributor Ha, I illustrate a heat exchangerbb. Below the lower distributor Illa I extend the inner cylinder 'Ba as at 61) to a level below the bottom I51), and I outwardly expand the outer cylinder as at 101), to form a circumferential receiver. This receiver is connected by the ductifia with the heat exchanger 5b. The duct 40a extends from the condenser directly to therec'eiver about the bottom of the combined evaporator receiver structure.

It will be understood that whereas I have shown stantially cylindrical, and to deform the outer cylinder instead. Note that the bottom l5b of Fig. 7 is located above the level of the receiver IOa; It will be understood that while the height of the bottom may be varied, the arrangement shown in Fig. 7 is advantageous. In the form of Fig. 7 note that the insulating disc Sta fills the space within the lower end of the cylindrical structure and is cut down outwardly and provided with a thin circumferential portion lilb which underlies the relatively loose insulation 64a. It may not be necessary to employ the downward extension I50. of the bottom l5.

Note that all joints -or sealing lines between 'the'two cylinders 5a and 6a may be obtained by welding. Thus although only two parts, the inner and outer cylinders, need not be employed,

they are so connected as to provide a series of entirely separated chambers including the receiver Illa at the bottom, the evaporator space, the.

upper and lower distributors, and finally the heat interchanger 51) at the top.

Referring to the form of the evaporator it may be varied substantially within the scope, of-my invention. Since the upper distributor?! must accommodate evaporated refrigerant, it is shown as larger than the bottom distributor ID. The details of the spacers l3 may be widely varied andI may for example employ ridges or projections of other form. I It is-immaterial whether the projections I 3 and the intermediate distributors M are formed in the inner or in the outer cylinder. It will be understood that it may be advantageous to have the inner surface of the inner cylinder cylindrical and flush. But the distributors 9 and It), the intermediate spacers l'e, the intermediate distributors l4, and the heat exchanger 5a and the receiver Illa may some or all of them be formed in the inner rather than in the outer cylinder, if desired. v 7

It will be realized that whereas I have described and shown a practical and operative device, nevertheless many changes may be made in the size, shape, number and disposition of parts without departing from the spirit of my invention. I therefore wish my drawings and description to be taken as in a broad sense illustrative and diagrammatic.

- The use and operation of my invention are as follows:

' I provide an evaporator structure for refrigerators which circumferentially defines and surrounds a storage space. I In the use of the device herein shown, the'storage space may be employed to receive and store foods or other substances.

It may be cooled sufficiently to treat materials, such as metals, where'cold temperature treatment is desired.

I provide an evaporator structure which hasan effective cooling surface throughout its entire inner area. The relation between the cooled area of the evaporator and the volume of the space cooled is such that I obtain a substantial avoidance of any temperature differential between the stored material and the refrigerant which would be effective to cause thermosyphonic action. This is particularly important in connection with the storage of food stuffsfsuch as meats. The result is an avoidance of"det'erioration or desiccation of the stored substances'and the reduction to a minimumof the depth of frost on the inner surface of the evaporator.

I also provide an evaporator which is economical to manufacture, which is highly -efficient in operation and which constitutes an adequate central frame or support or skeleton for the refrigerator. The outer and inner cylinders 5 and 6 may be truly cylindrical or they may be slightly cheap to manufacture and sturdy in use, and

which serves as the skeleton'or framework of the liquid unexpanded form, flows along the inlet ll completed refrigerator. In the actual manufacture of the device after 'the' two cylinders have been formed, they are interfitted or telescoped and are secured together at their upperand lower edges, and are provided with an ac'c'urate'clearance and proper final form by' the expansion of the inner cylinder 6 in relation to the outer cylinder 5. Any suitable spacing means may be employed but I find the integral dimples l3 highly efficient.

In the device of Figure 3, the refrigerant in to the bottom distributor ormanifold I0, which receives a substantial volume of the liquid. In the course of its evaporation, the refrigerant rises upwardly about the entire outer circumference of the inner cylinder 6. The spacers I 3 are of insufficient area to interfere with this upward rise. 'Thetop manifold or distributor 9 receives the refrigerant in evaporated or gaseous form and the gas passes oif through the discharge outlet I2. I findthat the intermediate and preferably smaller distributors M are of assistance in maintaining the uniform distribution of the refrigerant. In the preferred form of Fig. 7, the refrigerant flows in passage 40a from the condenser directly to the receiver lllb which forms part of the cylindrical structure and is housed within the insulation 64a. Liquid refrigerant flows thence along the passage lOd to the heat interchanger 5a. The object of passing the relatively warm liquid about A the top of the cylinder is to keep the rimof the cylinder at a higher temperature than the portion immediately below, to delay in part the formation of frost thereon. In fact, it is advan tageous if the extreme upper edge portion of the cylinder is actually warmer than the air which contacts it. Under those circumstances it tends to have lessattraction for moisture from outside air than would be the case if the top rim were as cool as the rest of the cylinder. t is at this point that I contact the cylinder with an insulating member as shown for example at 80. From the heat interchanger 5a the refrigerant flows to any suitable expansion valve 52a and thence' by the passage Ila to the lower distributor Illa. Finally the'evaporated refrigerant flows from the upper distributor 9:: back to the compressor along the duct l2a.

It will be understood that there is no metal path of heat transmission between the outer covering 63 and the evaporator structure... The member 65 may for example be formed of some suitable insulating material. Beneath it and between it and the insulation body .61 is a member of insulating material 80.

1. In anopen topped evaporator and stora e structure for refrigerators, concentric generally vertically axised inner and outer cylinders having spacing means adapted to space them slightly withdrawing eveporairedl re iorator space arbottom mem e aaaassrz i. arapartazsaid: cylinders-beingssealedttogether adjascent.their :ends-ato defineztherebetween an: evapcloratortspace; a bottommember closing-the storage zlflspfififl \aurroundedr by ?the: evaporatora spaceathus uiormeds: said -.-;cylindrical-: members c'being .addititionallyi separatedi-adiacentatheir 1. ppper: ends ,to ypruvide a generally :circnmeiIentia;lly-,; extending t cheat zirrterchanger space,- means ion-delivering. a Lnliqnidenefrigenantto.saidnheat! interchangen space a and, sthence etc: =saidsevape1ator,-. and means .for;

trigerant .irom .i the a exqaponator.

a 2min an epenxetoppedsevaporaton. and storage astnucture. ion meieigerators, .iconcentricv generally vertically axised inner andou-tercylindersthaving spacing neansz adapted".- .to space. them -.-slightly agapal, said pylindersebeing isealed -together adja- (fiiGfEDtli'il'lElIiEBIldS-ztO define.therebetweenan; evapber closing thestorage sgspaceizsurnoundedpby the evaporator space -'thus ;i.ormed, :said: cylindricali: members i being =.addi-' xqtionallyeisepara'ted adj acentntheir :upper ends. to g'providei genenally;tcircumierentially extending heat interchanger space rmeanslfondelivering a tiliquidmefiijigerant to said heat. interchanger space rand; :thence. .to.-.- sa-idrevapora=tor, and means 'for awithdrawingeevaporated zrefrigerant from the r' evaporator; lthe inner\. cylinderbeing generally c.eylindr-icatthreugho. ,tathe: .outer cylinder. having lzionmedi ithereim an outwardly extending portion,

defining isaidiineat 'interchanger space. Y .:.3;,-In-..an open toppedevaporatorand storage -,-.structure ior' reirigerators; concentric "generally i -vetical'ly axised inner and outer cylinders having spacingn-means=adapted-to 'space them slightly a. arpart said cylinders -being sealed =together adj a- .acent .theira-endsitow define therebetween an evap- :or-ator space asbottomrmemberclosing. the. storage .-;spacensurneundedzrby the. evaporator space-thus tor-medlsaid cylindrical members being sep arated .nad-jacent; their: upper.- and-lower ends to provide acireumfierentiab distributors i in communication withasaidevaporator space .and being additionally .zsseparatedi adjacent their -.uppe1=.-. ends -.to provide a;tgerrenally..circumterentiallye extending heatinterchangerrspace, means ion-delivering a liquid refrigerant; into said heat interchanger'space and .tthenceto one of thedistributors f saidevaporator Mandi means ton withdrawing .theevaporated reairigenant. irom .the- QDpDsite=- distributor, of the evaporator.

.-.4. .-In. .anepen .topped. evaporator and. storage aetructureafor refrigerators; concentric, generally vertically axised; inner.and-=outercylinders having spacing meansadapted to'spacethem-slightly .i apart said ,cylinders 1 being sealed together: to .edefinewtherebetweenaan evaporator space; a-botatom member closing theastoragespace surrounded "a by.t-he evaporator space thus formed, said cylin- .drical members being. additionally separated and sealedtogether adjacent theirv lower ends vto pro- .wide. a. generally.circumferentiallm extending' -receiver, passage means for delivering liquid refrigcrerantctoithe. receiver and from the :receiver to ..said evaporator. .space,.and means-for withdraw- Zring evaporated -refrigerant ,irom the: evaporator. ,5; In .an. evaporatornand.,storage structure for refrigerators? generally. concentric inner 1 and 1. outer .,cylindrical members ,spaced 1 apart.- .and

sealed together to define betweenthem a circumferentially extending evaporator, and...a circumierentially. extending receiver,..:and a. bottom elenmentimmediately above the receiver, the top of saidstructure. being .open l to provides; an" ,open atopnedistoragaspace.

H8 H5. In; amevaporator-and-.storage, structure :for 'refrigeriators; enerally concentric inner and-outer cylindrica'l memberstspaced apartand sealed-toi gethento define betweenthem a circumferentially e extending evapor-aton: anda. circumferentially extending rreceiver and a -.bottom:-:element. :rfor .-;said-'!str11cture,l the top of. saidstructure being -,op.en-;t o provideaamopentopped storage space, said 9; receiv=er-. being located abelowwthe. level. ,ot said lor'bottonr element.

1.11m .anevaporator and storage structureior '-.refrigerators, generally .-.concentric inner .and outer cylindrical; members spaced apart wand s sealed together todefine between them a circum- 5 .-:ter.entia1ly extending.evaporator -and a circumwaizerentiallyextending heat exchanger, and a botatomtelementitorv said-structure,-.the .top of-.-said "structure -be1-ng open to provide an ,opern topped astorage space; -said'heatexchanger-being located ..adjacent the .upperedgeof the storage structure. w .8.-.Inean evaporaton and storage structure for refrigerators, an open! .toppedastor-age member hincludi-nga a -=;generally cylindrical evaporator, H means- 401' withdrawing: evaporated r-teirigerant 5-, from said: evaporatorand :means. for. delivering "refrigerant 'toasaid evaporator..- including a.- heat exchanger-z extending. about the i ipper; ed e of -...said evaporatore ands: adapted-to.-"maintain.,the upper -.edge of the :storage' memben at a relatively high temperature.

9.1 Inaan. evaporator-.andstoragev structure for t -reirigerators, an --openw topped storage-1 .member including a generallycylindrical evaporator and a bottom-wall,- a heat: interchanger :formed. uni- :.tarily.- with gsaid'; evaporator, Y a. receiveniormed r:uni-tarily with. saideevaporator: means iordeliv- :ering-a-liquid refrigerant to said receiver means .,-.fior delivering liquidl-refrigerantfrom said weticeiverito [said heat interchanger,- means, includ- 0..i*ng-, pressure reducing means; tor .deliverimggrefrigerant to said evaporator and means tor with- .cdrawingievaponated aefrigerantrfrom said evapo- .rator.

...10.-..In-.-an evaporator andstorage structure ioi iirefrigerators, an; open toppedestorage member including: a generally cylindrical: evaponaton'and a bottom wall,- a heat interchanger formed: uni- .tarily-withsaid. evaporator, a. receiver for-med unitarily with said evaporator means .ior deliveringt a. liquid=nefrigerant to said receiver, means for delivering liquid refrigerant from said-receiver ....to-said.-heat. interchanger, means,- i-ncluding'presi sure reducingrmeans, for: delivering refrigerant ...to. said= evaporatora-ndmeans for withdrawing 55, evaporatedrefrigerant-from said evaporator; and a. b'o,dy. of insulation surrounding said evaporator a andlsaidrreceiver.

l.11....In; a. refrigerator; a -base; an: evaporator and storage structure, definingean open atopped 0. storage; zone, .mounted. -10Il -said.-.base;and:.inc1udtrig agenerallycylindrical evaporator and -a'-.-bottom wall,aa.-..heat interchanger and-1a receiver -=formed..uni.tarily with said evaporator, and are- =iriger-ant mechanism and circuit! including armo- ..torrcompressor-condenser unit mountecb 101'! :said a base,- a duct extending aflflm the conde'nser to'the z receiver aduct extendingfirom the'receiver'tothe f heat. interchanger, 1 a. duct-1' "extending from: (the i. heat: interchanger to the-evapor'ator; pressure reduc-ing means init-he" line of delivery'oi saidduct, 4 and a return duct'extending from the evaporator to theicompressor.

12. Inuaarefri-geratona base; an evaporator and atstorfige 'structura (defining anopen'topped storage 1': wnmmountednontsa'ida hasetands-including a generally cylindrical evaporator and a bottom wall, a receiver formed unitarily with said evaporator, a refrigerant mechanism and circuit, including a motor-compressor-oondenser unit mounted on said base, a duct extending from the condenser to the receiver, a duct extending from the re ceiver to the evaporator, pressure reducing means in the line of delivery of said duct, and a return duct extending from the evaporator to the compressor.

13. In a refrigerator, a base, an evaporator and storage structure, defining an open topped storage zone, mounted on said base and including a generally cylindrical evaporator and a bottom wall, a heat interchanger and a receiver formed unitarily with said evaporator, and a refrigerant mechanism and circuit including a motor-compressor-condenser unit mounted on said base, a duct extending from the condenser to the heat interchanger, a duct from the receiver to the heat interchanger, a duct extending from the heat interchanger to the evaporator, pressure reducing means in the line of delivery of said duct, and a return duct extending from the evaporator to the compressor, a layer of insulating material between said base and said evaporator and storage structure, upon which said evaporator and storage structure rests, a layer of insulating material surrounding said evaporator and, storage structure, an outer-generally cylindrical housing surrounding said insulating layer, said evaporator and storage structure constituting the reinforcement and support for said insulating layer and outer housing.

14. In a refrigerator, a base, an evaporator and storage structure, defining an open topped storage zone, mounted on said base and including a generally cylindrical evaporator and a bottom wall, a receiver formed unitarily with said evaporator, a refrigerant mechanism and circuit, including a motor-compressor-condenser unit mounted on said base, a duct extending from the condenser to the receiver, a duct extending from the receiver to the evaporator, pressure reducing means in the line of delivery of said duct, and a return duct extending from the evaporator to the compressor, a layer of insulating material between said base and said evaporator and storage structure, upon which said evaporator and storage structure rests, a layer of insulating material surrounding said evaporator and storage structure, an outer generally cylindrical housing surrounding said insulating layer, said evaporator and storage structure constituting the reinforcement and support for said insulating layer and outer housing.

15. In a refrigerator, an open topped evaporator-storage element adapted to surround a storage space, insulation means extending beneath and about said element, means for circulating a volatile refrigerant through the evaporator component of said element, a removable cover for said element and means for heating the upper edge of said element, at a level above the evaporator component and for thereby reducing frosting.

16. In a refrigerator, an open topped evaporator-storage element adapted to surround a storage space, insulation means extending beneath and about said element, means for circulating a volatile refrigerant through the evaporator component of said element, a removable cover for said element and means for heating the upper edge of said element, at a level above the evaporator component and for thereby reducing frosting, said means including a heat interchanger, in the line of delivery of refrigerant to the evaporator, extending about the upper edge of said element.

WILLARD L. MORRISON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,135,091 Newill Nov. 1, 1938 2,183,509 Smith Dec. 12, 1939 2,232,862 Genova May 12, 1942 2,349,695 Beane May 23, 1944 2,356,779 Morrison Aug. 29, 1944 2,381,617 Phel-an Aug. 7, 1945 

